Development inhibitor releasing compounds and their use in photographic materials

ABSTRACT

Development inhibitor releasing compounds of the formula ##STR1## are provided wherein R 1  is hydrogen or a substituent which may contain a long chain ballasting group and n is 1 or 2, or R 1  may form an annelated ring, R 2  is hydrogen or alkyl having 1 to 4 carbon atoms, R 3  is alkyl, aryl or aralkyl, Y is hydrogen, halogen, optionally substituted phenyl, --COOR 4 , --COR 4 , ##STR2## or --OR 4  where R 4  is alkyl or aryl or a group ##STR3## where Z represents the atoms necessary to complete an optionally substituted 5- or 6-membered heterocyclic ring which optionally may be benzannelated. 
     The new DIR-compounds form colorless compounds when reacted with the oxidation products of the color developing agent. They have an extremely high reactivity with the oxidation products of the color developing agent so that only small quantities of the DIR-compounds are required to produce excellent intra-image and inter-image effects of excellent speed.

The present invention relates to novel chemical compounds and to theiruse as photographic development inhibitor releasing compounds.Development inhibitor releasing compounds are hereinafter referred to asD.I.R. compounds.

According to the present invention there are provided compounds of thegeneral formula ##STR4## wherein R₁ is hydrogen or a substituent whichmay contain a long chain ballasting group and n is 1 or 2, or R₁ mayrepresent the atoms necessary to complete an annelated ring, R₂ ishydrogen or alkyl having 1 to 4 carbon atoms, R₃ is alkyl, aryl oraralkyl, y is hydrogen, halogen, optionally substituted phenyl, --COOR₄,--COR₄, ##STR5## or --OR₄ where R₄ is alkyl, aryl or a group ##STR6##where Z represents the atoms necessary to complete an optionallysubstituted 5- or 6-membered heterocyclic ring which optionally may bebenzannelated.

Preferably there is present in the compound a long chain alkylballasting group. This group may be present in R₁ or it may be presentin Y when Y is the group ##STR7## or it may be R₃.

Examples of R₁ are hydrogen, hydroxy, halogen, (fluorine, chlorine,bromine), nitro, hydroxymethyl, alkyl or alkoxy of 1 to 18 carbon atoms,--NHCOR₄, --NHSO₂ R₄, --COOR₄, --NH₂, --COOH, --SH, --SR₄ where R₄ is asdefined above.

Preferred meanings of R₁ are hydrogen, hydroxy, halogen (bromine) oralkoxy of 6 to 18 carbon atoms.

Preferably Y is hydrogen, halogen (chlorine, bromine), optionallysubstituted phenyl or a group ##STR8## as defined above.

Preferably the group ##STR9## is an optionally substituted triazole,tetrazole, benzimidazole, urazole, pyrazole, phthalimido or succinimidogroup; triazoles, benzimidazoles and urazoles are mostly preferred.

Suitable substituents are alkyl of 1 to 4 carbon atoms, alkylmercapto of1 to 8 carbon atoms, nitro, phenyl and/or benzyl.

A preferred class of the compounds of formula (1) are those of formula##STR10## wherein Y, R₂ and R₃ are as defined above and R₁ ' is hydroxy,alkoxy of 1 to 18, preferably of 6 to 18 and most preferably of 12 to 18carbon atoms or halogen (bromine).

Conveniently the alkoxy group has an alkyl moiety containing at least 6carbon atoms which helps to render the compound substantive in any layerin which it is coated and also helps to render it oil soluble.

Also preferably in the compounds of formula (2) R₂ is hydrogen and R₃ isalkyl having from 4 to 12 carbon atoms.

A particularly preferred class of compounds of formula (2) are compoundsof the general formula ##STR11## wherein R₃ ' is alkyl having from 6 to12 carbon atoms.

Another preferred class of compounds of formula (2) are the compounds offormula ##STR12## where R₅ is alkyl having at least 12 carbon atoms, R₃' is alkyl having from 6 to 12 carbon atoms and the group ##STR13## isan optionally substituted triazole, tetrazole, benzimidazole, urazole,pyrazole, phthalimido or succinimido group, with substituents asmentioned above.

Another useful class of compounds of formula (1) are compounds offormula ##STR14## where Y, R₂ and R₃ are as defined above and L is a--SO₂ or --CO-- link and R₆ is alkyl comprising at least 12 carbon atomsor is a group which comprises such an alkyl group.

The compounds of formula (1) couple with the oxidation products of acolour developing compound of the paraphenylene diamine type to yield acolourless coupler and the alkylthiotriazole group is liberated. Thisgroup is a D.I. compound.

According to another aspect of the present invention there is provided alight-sensitive photographic material which comprises, coated on aphotobase, at least one silver halide emulsion layer, the said emulsionlayer or a layer adjacent thereto comprising a compound of the generalformula (1).

Preferably the compound of formula (1) is a present in the silver halideemulsion layer.

In the preferred compounds of Formula (4) both the group ##STR15## andthe group ##STR16## which are attached to the central methine group ofthe compound are electron withdrawing groups. This means that themethine group is an activated methine group which can couple withoxidised colour developers of the paraphenylene diamine type in the sameway as colour couplers couple with such oxidised colour developers. Thecoupling of the compound of formula (1) with oxidised colour developerleads to an unstable compound in which elimination occurs and thealkylthiotriazole group is released.

Release of the alkylthiotriazole group from the compound of formula (1)also occurs on the coupling reaction with oxidised colour developer whenY in formula (1) is hydrogen, but not so readily in the compounds offormula (3).

When Y is halogen release of the alkylthiotriazole occurs readily butsome loss of photographic speed of the photosensitive silver halideemulsion is found to occur. The alkylthiotriazole is more efficacious asa D.I. compound when R₂ is hydrogen and R₃ is alkyl having from 4 to 12carbon atoms.

Thus preferably in the compound of formula (1) R₂ is hydrogen and R₃ isalkyl having from 4 to 12 carbon atoms.

The alkylthiotriazoles are released readily during the coupling reactionwith oxidised colour developer when Y is the group ##STR17## without anyconcomitant loss of speed of the emulsion.

Thus preferably in the compound of formula (1), Y is the group ##STR18##Also preferably the ballasting group is part of R₁.

By ballasting alkyl group is meant a straight or branched chain alkylgroup, optionally substituted, having at least 6 carbon atoms. Thepresence of the ballasting alkyl group in the D.I.R. compound rendersthis compound substantive to the layer in which it is coated.

Compounds of the above formula (1) may be prepared by reacting asolution of a compound of the general formula ##STR19## with analkylthiotriazole of the general formula ##STR20## wherein R₁, R₂ and R₃have the meanings assigned to them above, to yield a compound of formula##STR21## This is a compound of formula (1) when Y is hydrogen.

Compounds of formula (8) may be converted to compounds of formula (1)when Y is halogen by halogenation of the compound of formula (8) eitherin chloroform or in acetic acid medium. For example bromination inchloroform medium yields a compound of the general formula ##STR22##

Compounds of formula (9) may be converted to compounds of formula (1)for example wherein Y is the group ##STR23## by reacting compounds offormula (9) with a compound of the formula ##STR24## in the presence ofa base or with a potassium salt ##STR25## in acetonitrile.

Preferably the base used in the above preparations is pulverisedpotassium hydroxide.

The alkylthiotriazole compound which is of formula (7) is a D.I.compound. The use of compounds which release D.I. compounds imagewise iswell known in the photographic art to produce useful inter-layer andintra-layer effects.

While various development inhibitor-releasing compounds have beenproduced hitherto the majority of these compounds are not completelysatisfactory. For example in the case of a development inhibitorreleasing compound which forms a dye upon colour development, the colourcoupler residue of D.I.R. compound must be carefully selected to achievethe correct colour balance in the photographic colour image because ofthe specific absorption properties required of the resulting dye. It hasproved difficult to produce useful D.I.R. colour couplers.

On the other hand those development inhibitor releasing compounds whichform no dye with the oxidation products of a colour developing agenteither possess extremely low reactivity or cause serious speed lossduring development.

However the compounds of the present invention form colourless compoundswhen reacted with the oxidation products of the colour developing agent.The colourless residue does not constitute any part of the resultingimage. This has the advantage that the novel releasing compounds can beapplied to any required layer in the photographic material. Furthermore,the compounds of the present invention have an extremely high reactivitywith the oxidation products of the colour developing agent. Consequentlyonly small quantities of compound are required to produce excellentintra-image and inter-image effects without serious speed losses.

In yet another aspect of the present invention there is provided aprocess for the production of a photographic image which comprisesimagewise exposing a light-sensitive photographic silver halide materialwhich comprises in at least one silver halide layer or a layer adjacentthereto a compound of formula (1) and developing the exposed silverhalide with a paraphenylenediamine colour developing agent thereby toliberate imagewise the alkylthiotriazole compound of formula (7).

The D.I.R. compounds of the present invention may be used in anyphotographic product which can be processed by a chromogenic process andin which increased image sharpness and/or interlayer effects aredesired. Thus the greatest use of the D.I.R. compounds of the presentinvention is expected to be in the field of colour photographic materialand in particular in colour negative film material. When used in colourfilm material it is expected that the D.I.R. compounds of the presentinvention will be present in colour-sensitised silver halide emulsionlayers which comprise at least one colour coupler. Useful amounts ofD.I.R. present in such silver halide emulsion layers are 5-10 mole % ofthe colour coupler present.

Examples of specific compounds according to the present invention whichrelease a development inhibitor compound on coupling are: ##STR26##

In the following Examples parts and percentages are by weight.

EXAMPLE 1 Preparation of2-[3(5)-heptylthiotriazolyl]-2'-tetradecyloxyacetophenone (compound offormula (10))

A solution of 2'-tetradecyloxyphenacyl bromide (10 g) in warmacetonitrile (30 ml) was added to a solution of 3(5)-heptylthiotriazole(6 g) and triethylamine (3 g) in acetonitrile (20 ml). The reactionmixture was stirred at room temperature for 6 hours and then evaporated.The residue was dissolved in ethyl acetate (50 ml) and the organic layerwashed with water (2×50 ml), dried over MgSO₄, filtered and evaporated.Recrystallisation of the residue from methanol gave the compound offormula (10) as a fine white powder (7.8 g, 61%) m.p. 61°-62° C. (Found:C, 69.97; H, 9.41; N, 7.91% C₃₁ H₅₁ N₃ O₂ S requires: C, 70.27; H, 9.70;N, 7.93%).

EXAMPLE 2 Preparation of 2-bromo-[3(5)-heptylthiotriazolyl]-2'-tetradecyloxyacetophenone (compound of formula(14)).

To a stirred solution of compound 10 (5.1 g) in chloroform (75 ml) at60° C. was added over a period of 2 hours a solution of bromine (1.6 g)in chloroform (10 ml). The reaction mixture was stirred at refluxtemperature for a further 2 hours and then evaporated. Trituration ofthe residual oil in methanol at 0° C. afforded the product in solidform. Subsequent filtration gave the compound of formula (14) as a finewhite powder (5.4 g, 92%) m.p. 45°-46° C. (Found: C, 60.85; H, 8.20; N,7.1%. C₃₁ H₅₀ BrN₃ O₂ S requires: C, 61.11; H, 8.27; N, 6.9%).

EXAMPLE 3 Preparation of2-[3(5)-heptylthiotriazolyl]-2-[5,6-dinitrobenzimidazolyl]-2'-tetradecyloxyacetophenone(compound of formula (15)).

A mixture of the potassium salt of 5,6-dinitrobenzimidazole (2.6 g) and2-bromo-2-[3(5)-heptylthiotriazolyl]-2'-tetradecyloxyacetophenone (5.3g) in acetonitrile (50 ml) was stirred at 40° C. for 5 hours thenevaporated. The residue was dissolved in chloroform and the organiclayer washed with water (2×50 ml), dried over MgSO₄, filtered andevaporated. Recrystallisation of the residue from methanol gave thecompound of the formula (15) as a white solid (4.4 g, 68%) m.p. 63°-64°.(Found: C, 61.80; H, 7.30; N, 12.72%. C₃₈ H₅₃ N₇ O₆ S requires C, 62.01;H, 7.25; N, 13.04%).

EXAMPLE 4 Preparation of2-[3(5)-heptylthiotriazolyl]-2-[3-t-butyl-5-methylthiotriazolyl]-2'-tetraecyloxyacetophenone(compound of formula (16)).

A solution of the potassium salt of 3-t-butyl-5-methylthio triazole (2.1g) in acetonitrile (25 ml) was added to2-bromo-2-[3(5)-heptylthiotriazolyl]-2'-tetradecyloxyacetophenone (6.0g) in acetonitrile (50 ml). The reaction mixture was stirred at 45° C.for 31/2 hours then evaporated. The residue was dissolved in chloroformand the organic layer washed with water, dried over MgSO₄, filtered andevaporated. The compound was purified by column chromatography.Recrystallisation from methanol gave the compound of formula (16) as afine white solid (2.7 g, 39%) m.p. 63° C. (Found: C, 65.36; H, 8.90; N,11.91% C₃₈ H₆₂ N₆ O₂ S₂ requires: C, 65.28; H, 8.93; N, 12.02%).

EXAMPLE 5 Preparation of2-[3(5)-heptylthiotriazolyl]-2-N-benzylphenylurazolyl]-2'-tetradecyloxyacetophenone(compoumd of formula (17)).

To a solution of2-bromo-2[3(5)-heptylthiotriazolyl]-2'-tetradecyloxyacetophenone (3.0 g)and benzylphenylurazole (1.4 g) in acetonitrile (35 ml) was addedpulverized potassium hydroxide pellets (0.45 g). The reaction mixturewas stirred at room temperature for 2 hours, filtered and evaporated.Recrystallisation of the residue from methanol gave the compound offormula (17) as a fine white powder (2.3 g, 58%) m.p. 48°-49° C. (Found:C, 69,17; H, 7.80: N, 10.41%. C₄₆ H₆₂ N₆ O₄ S requires: C, 69.40; H,7.86; N, 10.57%).

EXAMPLE 6 Preparation of2-[3(5)-hexylthiotriazolyl]-2-phenyl-4'-tetradecyloxyacetophenone(compound of formula (18)). (a) 4-tetradecyloxyphenyl-benzyl ketone

To a solution of 4-hydroxyphenyl-benzyl ketone (10.5 g) in a solution ofpotassium hydroxide (3.0 g) in ethanol (100 ml) was addedtetradecylbromide (16 g). The reaction mixture was stirred at gentlereflux temperature for 12 hours, cooled and poured into water. Theproduct was extracted into chloroform, washed further with water, driedover MgSO₄, filtered and evaporated. Recrystallisation of the residuefrom methanol gave the above compound as a colourless crystalline solid(17.5 g, 86%) m.p. 72°-74° C.

(b) 2-bromo-2-phenyl-4'-tetradecyloxyacetophenone

To the above ketone (8.0 g) in chloroform (50 ml) containing zincchloride (0.2 g) was added a solution of bromine (3.2 g, 1.1 ml) inchloroform (25 ml). The reaction mixture was stirred at 35° C. for 31/2hours and evaporated to dryness. Recrystallisation of the residue frommethanol afforded the 2-bromo derivative as a fine white solid (8.1 g,85%) m.p. 62°-65° C.

(c) 2-[3(5)-hexylthiotriazolyl]-2-phenyl-4'-tetradecyloxyacetophenone(compound of formula (18)).

To the above 2-bromo compound (4.9 g) and 3(5)-hexylthio-1,2,4-triazole(2.0 g) in acetonitrile (35 ml) was added pulverised potassium hydroxidepellets (0.6 g). The reaction mixture was stirred at room temperaturefor 6 hours, filtered and evaporated. The residue was triturated at 0°C. in methanol to give the compound of formula (18) as a white solid(2.7 g, 46%) m.p. 54°-58° C. (Found: C, 72.86; H, 9.00; N, 7.10%. C₃₆H₅₃ N₃ O₂ S requires: C, 73.01; H, 9.03; N, 7.13%).

EXAMPLE 7: Preparation of2-[3(5)-hexylthiotriazolyl]-2'-hydroxyacetophenone (compound of formula(13)).

2-[3(5)-Hexylthiotriazolyl]-2'-tetradecyloxyacetophenone (prepared in ananalogous manner to the compound of formula (10)) (5.2 g) was stirred atgentle reflux with hydrobromic acid (48%, 60 ml) for 5 hours, cooled andpoured into water. The aqueous medium was neutralised with sodiumhydroxide solution and extracted with ether. The ether extract waswashed with water, dried over MgSO₄, filtered and evaporated to give acrystalline product. Trituration of the residue with petrolether(60°-80° C.) gave compound 13 as a white solid (2.3 g, 69%) m.p. 62°-65°C. (Found: C, 60.25; H, 6.64; N, 13.2%. C₁₆ H₂₁ N₃ O₂ S requires C,60.16; H, 6.63; N, 13.16%).

EXAMPLE 8 Preparation of 2-[3(5)-heptylthiotriazolyl]-2-[5,6-dinitrobenzimidazolyl]-2'-hydroxyacetophenone (compound of formula (19))

In an analogous manner to the preparation of the compound of formula(13) the compound of formula (19) was prepared from the compound offormula (15) as produced in Example 3 by reaction with hydrobromic acidunder reflux conditions for 5 hours.

EXAMPLE 9 (Use example)

1-(2,4,6-Trichlorophenyl)-3-(3-[(2,4-ditertamylphenoxy)acetamido]-benzamido)-5-pyrazolone(10 g) was dissolved in a solution of tricresyl phosphate (10 g) andethyl acetate (10 g) (coupler emulsion). A solution of gelatin (80 g)was added followed by water (20 ml) and 20 ml of a wetting agent (10%aqueous solution of the sodium salt of diisobutyl naphthalene sulfonicacid). The whole was then dispersed using an ultrasonic mixer.

The above coupler emulsion (24 g) was added to a silver iodobromideemulsion (40 g) having a silver content of 4.9 g and an average iodidecontent of 8.8 molar percent. Gelatin solution (48 g) and further 3.8 mlof the wetting agent were added and the whole made up to 200 g withwater.

The mixture was coated onto subbed triacetate film base to give a silvercoating weight of 20 mg per dm² and a coupler coating weight of 6.4 mgper dm². Above this was coated a 20 mg per dm² gelatin layer containinga triazine hardener.

The coating was exposed to a continuous wedge and then subjected to thefollowing processing sequence at 37.8° C.

1. Colour development 3.25 mins

2. Bleaching 6.50 mins

3. Washing 3.25 mins

4. Fixing 6.50 mins

5. Washing 3.25 mins

6. Stabilizing 1.50 mins.

The processing baths had the following compositions.

    ______________________________________                                        1. Developer                                                                  ______________________________________                                        Potassium carbonate      37.5   g                                             Sodium metabisulphite (anhydr.)                                                                        4.25   g                                             Potassium iodide         2.0    mg                                            Sodium bromide           1.3    g                                             Hydroxylamine sulphate   2.0    g                                             4-(N-ethyl-N-β-hydroxyethylamino)-                                       2-methylaniline sulphate 4.75   g                                             Water to 1 litre.                                                             ______________________________________                                    

    ______________________________________                                        2. Bleaching bath                                                             ______________________________________                                        Ammonium bromide        150     g                                             Ferric ammonium ethylenediamine                                               tetra-acetic acid       175     ml                                            Glacial acetic acid     10.5    ml                                            Sodium nitrate          35      g                                             Water to 1 litre.                                                             ______________________________________                                    

    ______________________________________                                        4. Fixing bath                                                                ______________________________________                                        Ammonium thiosulphate (50%)                                                                            162     ml                                           Diethylene triamine penta-acetic acid                                                                  1.25    g                                            Sodium metabisulphite (anhyd.)                                                                         12.4    g                                            Sodium hydroxide         2.4     g                                            Water to 1 litre.                                                             ______________________________________                                    

    ______________________________________                                        6. Stabilizer                                                                 ______________________________________                                        35% formaldehyde solution                                                                             5.0 ml                                                Water to 1 litre.                                                             ______________________________________                                    

The above procedure (CONTROL) produced the following photographicresults for maximum contrast (γm) and contrasted adjusted speed (S γ/4):

    ______________________________________                                        Control        γm  Sγ/4 (log E units)                             ______________________________________                                        Pyrazolone                                                                    coupler alone  1.30      2.73                                                 ______________________________________                                    

To allow for the effect of contrast on foot speed the S γ/4 value hasbeen quoted. This is defined as:

    S γ/4=(Speed at a density level of fog)+γ/4.

The above coating procedure was then repeated but in addition to thepyrazolone coupler, coatings were made which individually incorporated 5or 10 mole percent of D.I.R. compounds, and the percentage γmsuppression and change in S γ/4 compared with the control were measured.

                  TABLE 1                                                         ______________________________________                                                         % γm  Change in                                        D.I.R. compound  suppression S γ/4                                      ______________________________________                                        5% level of compound (10)                                                                      26          +0.01                                            10% level of compound (10)                                                                     35          +0.01                                            10% level of compound (12)                                                                     19          +0.03                                             5% level of compound (13)                                                                     43          +0.02                                             5% level of compound (14)                                                                     53          -0.02                                             5% level of compound (15)                                                                     38          +0.01                                            ______________________________________                                    

Table 1 clearly shows that the compounds of the present invention can beused to inhibit development as shown by the high γmax suppressionvalues. The compounds can be chosen to provide a range of D.I.R.activity. Furthermore the D.I.R. compounds of the present invention,with the exception of the compound of formula (14), show no speed lossas shown by the positive S γ/4 values.

EXAMPLE 10 (Use example)

Further coatings as prepared in Example 9 were exposed to a line andspace chart at a range of exposures and subjected to the processingsequence as before.

Using a microdensitometer the density difference for each line and spacefrequency were calculated. The relative response was then calculated bynormalising the density difference at each frequency to that of thelowest frequency.

As relative response changes with exposure the results quoted wereaveraged over the exposure range.

                  TABLE 2                                                         ______________________________________                                                       Relative Response                                              D.I.R. compound  7 lines/mm  35 lines/mm                                      ______________________________________                                        None (pyrazolone                                                              coupler alone)   0.87        0.40                                             10% level of compound (10)                                                                     0.99        0.52                                              5% level of compound (13)                                                                     1.01        0.56                                             10% level of compound (14)                                                                     1.00        0.44                                             ______________________________________                                    

Table 2 shows clearly that the D.I.R. compounds of the present inventionexhibit increased sharpness when compared with the control coating.

I claim:
 1. A light-sensitive photographic material which comprises,coated on a support base, at least one silver halide emulsion layer, thesaid emulsion layer or a layer adjacent thereto comprising a compound ofthe general formula ##STR27## wherein R₁ is hydrogen, hydroxy, halogen,nitro, hydroxymethyl, alkyl, alkoxy of 1 to 18 carbon atoms, --NHCOR₄,--NHSO₂ R₄, --COOR₄, --NH₂, --COOH, --SH, --SR₄ where R₄ is as definedbelow and n is 1 or 2, R₂ is hydrogen or alkyl having 1 to 4 carbonatoms, R₃ is alkyl, aryl or aralkyl, Y is hydrogen, halogen, optionallysubstituted phenyl, --COOR₄, --COR₄, ##STR28## or --OR₄ where R₄ isalkyl or aryl or a group ##STR29## where Z represents the atomsnecessary to complete an optionally substituted 5- or 6-memberedheterocyclic ring or a 5- or 6-membered heterocyclic ring which isbenzannelated.
 2. Photographic material according to claim 1 wherein thecompound is present in the silver halide emulsion layer.
 3. A processfor the production of a photographic image which comprises imagewiseexposing a light-sensitive photographic silver halide material whichcomprises in at least one coloured-coupler-containing silver halidelayer or a layer adjacent thereto a compound of the general formula##STR30## wherein R₁ is hydrogen, hydroxy, nitro, hydroxymethyl, alkyl,alkoxy of 1 to 18 carbon atoms, --NHCOR₄, --NHSO₂ R₄, --COOR₄, --NH₂,--COOH, --SH, --SR₄ where R₄ is as defined below and n is 1 or 2, R₂ ishydrogen or alkyl having 1 to 4 carbon atoms, R₃ is alkyl, aryl oraralkyl, Y is hydrogen, halogen, optionally substituted phenyl, --COOR₄,--COR₄, ##STR31## or --OR₄ where R₄ is alkyl or aryl or a group##STR32## where Z represents the atoms necessary to complete anoptionally substituted 5- or 6-membered heterocyclic ring or a 5- or6-membered heterocyclic ring which is benzannelated. and developing theexposed silver halide with a paraphenylenediamine colour developingagent thereby to liberate imagewsie the development inhibitoralkylthiotriazole compound of the formula ##STR33## wherein R₂ and R₃have the meanings assigned to them in the general formula above.